In certain situations, it is desirable to enable data to be transmitted from a particular location in such a manner as to be disguised from receivers in the vicinity. In particular, personnel in hostile territory frequently desire to transmit a data signal to a remote, friendly receiver without detection by enemy receivers in the vicinity of the transmission site. Such a transmission scheme is desirably employed by military personnel, in behind the front activities, from portable transmitters, such as "man packs", or by clandestine "civilian" personnel from fixed transmission sites. It is also desirable for a transmitter for such purposes to be relatively jam proof and for the data signal to be coded, to decrease the possibility of deciphering a message, in the event that the disguised signal is detected.